So I believe what happened is there must have been a light coating on the cathode last night. As that wore away, the etching accelerated. Today I made a few changes, but I used that same piece, and the instant I put it in the tank and connected the wires, lots of bubbling/activity began to take place.

Attempt #2:

Using a proper battery this time

Oriented the 'etching surface' perpendicular to the cathode (in an attempt to make the surface as equidistant as possible), which means standing it upright

Annnd.... cathode failure (there was a hole through the part and a wire wrapped around it)

Now I'm wondering if I do a proper connection. Drill and tap the part, attach wire with a ring terminal, then seal it with silicone, preventing it from basically etching itself away.

Remember that aluminum forms a layer of oxide, that should be cleaned off first. Perhaps that’s what you burned through. Scotchbriting the piece before it goes in the tank will help

For an electrical connection, I’ve been able to successfully fan the wire out and just tape it to the clean surface. If you get a water leak, it’ll corrode. I’ve never run anything as deep as you have.

Its smith mountain lake. I've been going there since I was a kid. My parents retired there ~5 years ago. I making a piece of 'art' for my mom.

I was able to use Google Map Customizer to tinker with the CSS and basically show only water and land with in 2 flat colors. Then I did a little cleanup in photo software - removed the smaller waterways and some of the small islands. I set the resolution to something crazy like 5k x 5x and then used a scrolling-screencap plugin to take the screenshot (it takes a ton and splices them all) so I didn't lose the small details. I probably went overkill, but originally I was thinking of doing a piece up to 24" square, so a typical browser screenshot wouldn't cut it.

Cutting the final vinyl now, will try the etching with steel this afternoon.

Keith, could you provide a little more detail on the iron-on method you used on page 1 that allows for the use of a gradient? What specific paper did you use? Is that achievable in a standard inkjet printer?

Etching is done. I made the mistake of removing the mask early though.

Unlike aluminum, when steel is etched it doesn't provide a good contrast between the etched and un-etched surfaces :( If I left the mask on I could allow the etched areas to rust a bunch. But I didn't. Now my hope is to let all of it rust and then sand/polish down the raised areas, which will be quite difficult.

(This pic shows the best case contrast. If you look straight on its much harder to see)

So another update. I took the above piece and decided to let it rust a bit, then block sand down the top layer to get the contrast back. This did not work for 2 reasons:

1) the etching depth was not consistent. Near the center of the plate it was too easy to accidentally sand the etched areas instead of just the lake design.

2) The rust pitted the un-etched areas too much so I couldn't really sand it down enough to get the smooth metallic finish back. Oops.

Time for attempt # ??

This time I used the plate above as the anode for a new plate I was going to etch. To make sure the etching was consent, I held them offset from one another a fixed amount:

This worked really well except it draws ALL OF THE AMPS!. I really need to hook up a real 12v power supply so I can regulate the amperage. The etching only took a few minutes... the same amount of time it took to literally melt the wires running to it (oops) and totally drain the battery (oops).

This time I left the masking in place, painted it black, removed the masking (with trouble removing adhesive) then cleared it. The adhesive removal step was fairly abusive and involved a torch. (oops). But it got it done, and although it didn't come out how I wanted, it still looks cool, has some character, and my mom loves it.